Ontario is massive both in area and in population, with 50+ square miles of territory and 160,000+ residents. It is a part of the greater Inland Empire region, and more specifically, southwest San Bernardino County. Ontario borders Rancho Cucamonga, Fontana, Pomona, Chino, and several other smaller municipalities. One of Ontario's most defining features is its airport, which serves as a major cargo hub for the southwestern United States and employs nearly 8,000 residents.

Like much of the rest of the Inland Empire, Ontario is within a few miles of mountainous terrain, specifically Mt. Baldy and its friends in the San Gabriel range. This proximity lends the city a striking vista; moreover, residents can ski, snowboard, camp, hike, climb, etc. with relative convenience. Those who work in the Riverside or San Gabriel Valley areas might reasonably consider Ontario a viable hometown from which to commute, but those who work in Los Angeles will find that traffic and distance combine to render more-than-occasional trips to that area prohibitively time-consuming. Major arteries: the 60, 15, and 10 freeways.